The work presented in this thesis is an investigation into vehicle
bodyshell structural joints, with the aim of improving their stiffness.
The bodyshell joint is defined to be an area or sub-structure containing
the intersection of beam-type members, the behaviour of which may be
defined by a matrix determined experimentally or analytically by using
the finite element method. An actual bodyshell was tested on a suitably designed rig and the
primary displacement modes affecting the steady state and vibration
response of a bodyshell were identified and the relevant stiffness
measured by using a special transducer. The joint rotational displacements
were measured in these modes and the relative importance of the
joints obtained. The joints were then modified by the addition of
stiffening plates and the effect on the various stiffnesses noted. To assist the analyst, a similar study was performed on the
effectiveness of the panels, such as roof, floor and rear quarter. A
finite element beam model was established for the bodyshell and
modified until a good approximation was achieved with respect to
the experiments.
Some practical modification of three selected joints cut from
the bodyshell was done in order to improve their stiffness. A theoretical
study of the influence of spot welding size and spacing on the stiffness
of two plates was made. A finite element model of an actual body joint
was established and the effect on stiffness of various modifications
was observed.

Description:

A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.